Sample from the Everest Set.
Up until the early 1990's a company in Russia sold a periodic table collection with element samples. At some point their American distributor sold off the remaining stock to a man who is now selling them on eBay. The samples (except gases) weigh about 0.25 grams each, and the whole set comes in a very nice wooden box with a printed periodic table in the lid.

Radioactive elements like this one are represented in this particular set by a non-radioactive dummy powder, which doesn't look anything like the real element. (In this case a sample of the pure element isn't really practical anyway since the element exists as a short-lived laboratory curiosity only.)

Autographed card.
There are some elements you're just not going to get a sample of, and this is one of them. What can you do? Collecting autographs of the people involved in discovering the element is one thing. Greg P started the concept of getting element tiles autographed by their discoverers with a truly remarkable one: A tile of seaborgium autographed by Glenn Seaborg after whom it is of course named. Naming elements after a living person is unheard of except in that one very special instance, and it's definitely never going to happen again. Since Seaborg died not too long after his element was named, there existed only a very short period in human history, never to be repeated, when you could get the autograph of the person on an element tile named after them.
The tile pictured here is also autographed by its one of its co-discoverers, Dr. Gregory Choppin. Shawn Havery came up with the idea of replicating Greg's tiles for other elements, and I've been encouraging him to do as many as he can: There aren't going to be many more elements discovered, and the people alive who have created an element is small and not getting any bigger. We live in the unique couple of decades when it's possible to assemble such signed tiles. So what are you waiting for Shawn?Source:Shawn HaveryContributor:Shawn HaveryAcquired:12 September, 2003Price: DonatedSize: 3"Purity: 0%

Poster sample.
This photograph of Enrico Fermi appears in my Photographic Periodic Table Poster representing fermium, which is named after him. This highly unstable element can't reasonably be photographed, and a picture of its namesake seemed like a reasonable alternative. The sample photograph includes text exactly as it appears in the poster, which you are encouraged to buy a copy of.
This photo is used with permission of the US Department of Energy.Source:Max Whitby of RGBContributor:Max Whitby of RGBAcquired:15 April, 2006Text Updated:4 May, 2007Price: DonatedSize: 6"Purity: 0%